text: /**
  A character in UTF8 can be from 1 to 4 bytes long, subjected to the following rules:
  
  For 1-byte character, the first bit is a 0, followed by its unicode code.
  For n-bytes character, the first n-bits are all one's, the n+1 bit is 0, followed by n-1 bytes with most significant 2 bits being 10.
  This is how the UTF-8 encoding would work:
  
     Char. number range  |        UTF-8 octet sequence
        (hexadecimal)    |              (binary)
     --------------------+---------------------------------------------
     0000 0000-0000 007F | 0xxxxxxx
     0000 0080-0000 07FF | 110xxxxx 10xxxxxx
     0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
     0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
  Given an array of integers representing the data, return whether it is a valid utf-8 encoding.
  
  Note:
  The input is an array of integers. Only the least significant 8 bits of each integer is used to store the data. This means each integer represents only 1 byte of data.
  
  Example 1:
  
  data = [197, 130, 1], which represents the octet sequence: 11000101 10000010 00000001.
  
  Return true.
  It is a valid utf-8 encoding for a 2-bytes character followed by a 1-byte character.
  Example 2:
  
  data = [235, 140, 4], which represented the octet sequence: 11101011 10001100 00000100.
  
  Return false.
  The first 3 bits are all one's and the 4th bit is 0 means it is a 3-bytes character.
  The next byte is a continuation byte which starts with 10 and that's correct.
  But the second continuation byte does not start with 10, so it is invalid.
   * @param {number[]} data
   * @return {boolean}
   */
  var validUtf8 = function(data) {
  	var state = 0;
  	for (var i in data) {
  		var t = check(data[i]);
  		if (t === -2) {
  			return false;
  		}
  		if (state === 0 ||state > 0 && t === -1) {
  			state += t;
  		} else {
  			return false;
  		}
  	}
  	return state === 0;
  };
  
  function check(num) {
  	if (num > 255) {
  		return -2;
  	}
  	if (num >>> 7 === 0b0) {
  		return 0;
  	}
  	if (num >>> 5 === 0b110) {
  		return 1;
  	}
  	if (num >>> 4 === 0b1110) {
  		return 2;
  	}
  	if (num >>> 3 === 0b11110) {
  		return 3;
  	}
  	if (num >>> 6 === 0b10) {
  		return -1;
  	}
  	return -2;
  }
  
  
  console.log(validUtf8([235, 140, 4]))
  // console.log(validUtf8([197, 130, 1]))